{
  "resourceType" : "Order",
  // from Resource: id, meta, implicitRules, and language
  // from DomainResource: text, contained, extension, and modifierExtension
  "identifier" : [{ Identifier }], // Identifiers assigned to this order by the orderer or by the receiver
  "date" : "<dateTime>", // When the order was made
  "subject" : { Reference(Patient|Group|Device|Substance) }, // Patient this order is about
  "source" : { Reference(Practitioner|Organization) }, // Who initiated the order
  "target" : { Reference(Organization|Device|Practitioner) }, // Who is intended to fulfill the order
  // reason[x]: Text - why the order was made. One of these 2:
  "reasonCodeableConcept" : { CodeableConcept },
  "reasonReference" : { Reference(Any) },
  "when" : { // When order should be fulfilled
    "code" : { CodeableConcept }, // C? Code specifies when request should be done. The code may simply be a priority code
    "schedule" : { Timing } // C? A formal schedule
  },
  "detail" : [{ Reference(Any) }] // R!  What action is being ordered
}